Check debugging is enabled before restoring

src/index.ts

@@ -75,6 +75,10 @@ async function setDebugSession(
   } else {
     debug.session.client = client;
   }
+  const debuggingEnabled = await debug.requestDebuggingEnabled();
+  if (!debuggingEnabled) {
+    return;
+  }
   await debug.restoreState(true);
   app.commands.notifyCommandChanged();
 }
@@ -86,11 +90,15 @@ class DebuggerHandler<
     this.builder = builder;
   }
 
-  update<W extends ConsolePanel | NotebookPanel | FileEditor>(
+  async update<W extends ConsolePanel | NotebookPanel | FileEditor>(
     debug: IDebugger,
     widget: W
-  ): void {
-    if (!debug.model || this.handlers[widget.id] || !debug.isDebuggingEnabled) {
+  ) {
+    if (!debug.session) {
+      return;
+    }
+    const debuggingEnabled = await debug.requestDebuggingEnabled();
+    if (!debug.model || this.handlers[widget.id] || !debuggingEnabled) {
       return;
     }
     const handler = new this.builder({
@@ -138,7 +146,7 @@ const consoles: JupyterFrontEndPlugin<void> = {
         return;
       }
       await setDebugSession(app, debug, widget.session);
-      handler.update(debug, widget);
+      void handler.update(debug, widget);
     });
   }
 };
@@ -185,7 +193,7 @@ const files: JupyterFrontEndPlugin<void> = {
           activeSessions[model.id] = session;
         }
         await setDebugSession(app, debug, session);
-        handler.update(debug, content);
+        void handler.update(debug, content);
       } catch {
         return;
       }
@@ -209,7 +217,7 @@ const notebooks: JupyterFrontEndPlugin<void> = {
         return;
       }
       await setDebugSession(app, debug, widget.session);
-      handler.update(debug, widget);
+      void handler.update(debug, widget);
     });
   }
 };

src/service.ts

@@ -41,10 +41,11 @@ export class DebugService implements IDebugger, IDisposable {
   }
 
   /**
-   * Whether debugging is enabled for the current session.
+   * Request whether debugging is enabled for the current session.
    */
-  get isDebuggingEnabled(): boolean {
-    return this._session.kernelInfo?.debugger ?? false;
+  async requestDebuggingEnabled(): Promise<boolean> {
+    const kernelInfo = await this._session.requestKernelInfo();
+    return kernelInfo?.debugger ?? false;
   }
 
   /**

src/session.ts

@@ -66,17 +66,19 @@ export class DebugSession implements IDebugger.ISession {
       this._client.iopubMessage.connect(this._handleEvent, this);
 
       if (this.client instanceof ClientSession) {
-        this._ready = this.client.ready;
+        this._ready = this.client.ready.then(_ => this.client.kernel.ready);
       } else {
         this._ready = this.client.kernel.ready;
       }
     }
   }
 
   /**
-   * Return the kernel info for the debug session.
+   * Return the kernel info for the debug session, waiting for the
+   * kernel to be ready.
    */
-  get kernelInfo(): IDebugger.ISession.IInfoReply | null {
+  async requestKernelInfo(): Promise<IDebugger.ISession.IInfoReply | null> {
+    await this._ready;
     return (this.client.kernel?.info as IDebugger.ISession.IInfoReply) ?? null;
   }
 

src/tokens.ts

@@ -17,11 +17,6 @@ import { DebugProtocol } from 'vscode-debugprotocol';
  * An interface describing an application's visual debugger.
  */
 export interface IDebugger {
-  /**
-   * Whether debugging is enabled for the current session.
-   */
-  readonly isDebuggingEnabled: boolean;
-
   /**
    * The current debugger session.
    */
@@ -47,6 +42,11 @@ export interface IDebugger {
    */
   readonly eventMessage: ISignal<IDebugger, IDebugger.ISession.Event>;
 
+  /**
+   * Request whether debugging is enabled for the current session.
+   */
+  requestDebuggingEnabled(): Promise<boolean>;
+
   /**
    * Computes an id based on the given code.
    */
@@ -144,11 +144,6 @@ export namespace IDebugger {
      */
     client: IClientSession | Session.ISession;
 
-    /**
-     * The kernel info for the debug session.
-     */
-    readonly kernelInfo: IDebugger.ISession.IInfoReply | null;
-
     /**
      * Whether the debug session is started
      */
@@ -162,6 +157,12 @@ export namespace IDebugger {
       IDebugger.ISession.Event
     >;
 
+    /**
+     * Return the kernel info for the debug session, waiting for the
+     * kernel to be ready.
+     */
+    requestKernelInfo(): Promise<IDebugger.ISession.IInfoReply | null>;
+
     /**
      * Start a new debug session.
      */

tests/src/service.spec.ts

@@ -41,19 +41,21 @@ describe('Debugging Support', () => {
     await Promise.all([xpythonClient.shutdown(), ipykernelClient.shutdown()]);
   });
 
-  describe('#isDebuggingEnabled', () => {
-    it('should return true for kernels that have support for debugging', () => {
+  describe('#requestDebuggingEnabled', () => {
+    it('should return true for kernels that have support for debugging', async () => {
       const debugSession = new DebugSession({ client: xpythonClient });
       let service = new DebugService();
       service.session = debugSession;
-      expect(service.isDebuggingEnabled).to.be.true;
+      const enabled = await service.requestDebuggingEnabled();
+      expect(enabled).to.be.true;
     });
 
-    it('should return false for kernels that do not have support for debugging', () => {
+    it('should return false for kernels that do not have support for debugging', async () => {
       const debugSession = new DebugSession({ client: ipykernelClient });
       let service = new DebugService();
       service.session = debugSession;
-      expect(service.isDebuggingEnabled).to.be.false;
+      const enabled = await service.requestDebuggingEnabled();
+      expect(enabled).to.be.false;
     });
   });
 });